Problem: Solve for $x$ and $y$ using substitution. ${3x-2y = -4}$ ${y = -x-3}$
Answer: Since $y$ has already been solved for, substitute $-x-3$ for $y$ in the first equation. ${3x - 2}{(-x-3)}{= -4}$ Simplify and solve for $x$ $3x+2x + 6 = -4$ $5x+6 = -4$ $5x+6{-6} = -4{-6}$ $5x = -10$ $\dfrac{5x}{{5}} = \dfrac{-10}{{5}}$ ${x = -2}$ Now that you know ${x = -2}$ , plug it back into $\thinspace {y = -x-3}\thinspace$ to find $y$ ${y = -}{(-2)}{ - 3}$ $y = 2 - 3$ $y = -1$ You can also plug ${x = -2}$ into $\thinspace {3x-2y = -4}\thinspace$ and get the same answer for $y$ : ${3}{(-2)}{ - 2y = -4}$ ${y = -1}$